Nanocavities stabilize charge: Surface topology is a general strategy for controlling charge dissipation

Abstract

Strategies for controlling static charge on surfaces have always focused on charge generation. On the other hand, charge dissipation also plays a very important role in most current technologies: the rate of charge dissipation critically needs to be much slower for applications and much faster for eliminating the many undesirable effects of static charge in industry. Controlling charge dissipation is extremely difficult as it involves a gas-phase chemical reaction (i.e., ionization of gaseous molecules). This study reports for the first time that surface topology effectively controls charge dissipation. Charge dissipation is much slower for rough surfaces and much faster for smooth surfaces. The effect is great: a rough surface retains a remarkable 100 times more charge than a smooth surface during dissipation. This difference gives rise to a large difference in power produced by triboelectric generators by 104 times. This phenomenon is thus the much-needed solution for retaining charge for useful applications or eliminating charge to prevent the undesirable effects of static charge from occurring. Surface topology is a physical property, whereas ionization is a chemical reaction; thus, it is surprising that surface topology affects reaction. Static charge is found to correlate spatially with the nanoscale valleys of the rough surface. Therefore, the high curvature provided by the nanocavities of rough surfaces is the fundamental physical principle for stabilizing ions via dipole interactions with surface molecules and reducing ionization. Varying surface topology is thus an effective and simple strategy for either increasing or decreasing charge dissipation (e.g., for triboelectric power generator and electrostatic self-assembly).